Vibration measuring and indicating device



xR: 'zmamism J1me 30, 1936. M. N. FAIRBANK VIBRATION MEASURING AND INDICATING DEVICE 4 Sheets-Sheet 1 Filed July 21, 1934 BY A 'ITORNEYS ?a.-mEAsumN a & sme.

June 30, 1936 V M- NI'FA|RBANK 2,046,154

VIBRATION MEASURING AND INDICATING DEVICE Filed July 21, 1934 4 Sheets-Sheet 2 A XNVENTOR flairyjlffkriwzl BY%7M6 ATTORNEYs Y YaQPJuiADMw a Time.

- June 30, 1936. i M, NK 2,046,154

VIBRATION MEASURING AND INDICATING DEVICE Filed July 21, 1954 4 Sheets-Sheet a Illlllllllllllllll llllll flllllllllllllllllmlllllllllllllii lllllllllllllll INVENTOR flurry Afizirfianli %am4,6 Wm? ATTORN EYS Searcn mum m mmsums & Esme.

Mm 30, 1936. M. N. FAIRBANK v I VIBRATION MEASURING AND INDICATING DEVICE 4 Sheets-Sheet 4 Filed July 21, 1934 ATTORNEYS I WNVENTOR 1 J i i ZBJlVlEASURillG it TESTlNG.

Patented June 30, 1936 VIBRATION MEASURING AND INDICATING DEVICE Murry N. Fair-bank, Suffolk County, N; Y.

1 Application July 21, 1934, Serial No. 736.435

' 17 Claims. .(Cl. 73-51) along line 2--2 of Fig. 3 through the device as This invention relates in general to measuring instruments and more particularly to instruments for measuring the components of vibratory movement of a vibrating mass.

An object of the'invention is to provide a device for measuring and indicating the amplitude of vibration and the period, or frequency, of bodies, having a regular and reasonably steady vibrat l'y i es... i

1'0"""""'Ari0thl objectis to p ovi e an i proved means 2) components of movement separately. In other other than'those along the particularchosen axis.

for adjusting and maintaining the device in a state or resonancewiththe vibrations of the body .the motion of which it is desired to measure.

Another objectof the invention "is to provide a device for measuring the vibratory movements of an object in any one of a number of planets. Inasmuch as abody may vibrate in one or more directions it is an object of this invention to provide a. device for measuring each of these words, it is an object of this invention to providea device which will be sensitive along only one axis or in one direction at a time and be independent of and not sensitive'to vibrations It is a further object of theinven'tion to provide such a measuring device that it may be portable and hand-held against or'fa'stened to the vibrating body, the relative position of the device with the body depending upont-he particular component of vibrating movement being measured.

With these and other ends in view it is pro posed to provide a device in the form of a self contained portable unit. The unit includes a j include a device for applying to the frequency scale of the vibratory assembly a correction for 7 different amplitudes of motion of the vibrating body.

With the foregoing and other objects in view, the invention consists in the combination of parts I and in the details of construction hereinafter set iorth in the following specification and appended claims, certain embodiments thereof being illustrated in the accompanying drawings, in which:

Fig. l is a view in perspective of the device in its casing.

Fig. 2 is al-view in longitudinal section taken shown in Fig. 1.

of Fig. 2.

Fig. 41s a fragmentary view in section taken along line 4-4 of Fig. 2.

Fig. 5 is a view in section taken along of Fig. 3.

Fig. dis a view in of Fig; *5; Fig. 7 is a view in section takenalong line 1-7 of Fig. 5.

Fig. 3 is a. view in section taken along line V V line 5-5 's'ection'taken along line sis Fig. 8 is an. enlarged detail view in perspective of .the vibratory member, the spring and the vane. Fig. 9 is an enlarged detail view in perspective of the torsional spring and the adjustable carriage for varying its effective length.

Fig. 10 is an enlarged detail view of a resilient coupling for the frequency adjusting control;

Fig. 11 is a diagrammaticalshowing of the relationship of a medium amplitude with various frequencies. g g

' Referring more particularly to the drawings, Fig. 1 shows the self-contained unit assembled.

The casing consists preferably of a. light metalbox with side. walls 53, a bottom wall ill, a removable top plate 52 and front and rear end walls It and 8' respectively. 'To the rear wall 8 there may be secured an arm and hand pistol grip ll-by meansof a screw bolt 12 provided'with a knurled hand knob 13. The box isof such by gripping the pistol grip. In theiront wall there is provided an internally screw threaded beam 14 extending across the front wall of the case and receives a prong 22, which latter may be either'manually pressed against the vibrating body to beinvestigatedor suitably secured thereto.

The top plate 52 is slotted at two spaced intervals to render visible an amplitude scale 25 and a frequency scale 46. The top plate is also slotted at 15 to allow a rotatable manual adjustment wheel 55 to protrude-upwardly there through. Knob is a control knob for manual adjustment of the frequency'scale indicator.

The vibratory system as a unit is carried by a bar I of substantially square crosseection and this bar is apertured at its ends to receive the nonthreade d shanks of set screws 35" extending through the casing side walls and reinforcing blocks 36 secured thereto, the fit between the shanks and the apertures of the bar being such as to permit rotation of the bar and the assembly carried thereby.

A pair of sliders 2 are each apertur'ed'to' receive a light weight that it may be readily. hand-heldso as to be fixed thereto.

a bearing sleeve 16 for sliding engaged with bar I upon which the sliders are mounted. Each of these sliders has secured thereto at H a toothed rack 56. The racks extend from each slider in opposite directions but parallel and in the same. horizontal plane. The racks simultaneously engage a pinion 48, under the control of hand knob 4-3, for simultaneously moving the sliders either toward or away from each other according to the direction in which the knobis rotated. In order to provide for a wide range of relative movement between the sliders each of the same is perforated to allow the free end of the rack of the other to pass through the perforation. The guide bar I passes through a centrally located rigidframe 49 Each slider carried thereby is recessed at 78, the side walls of the recesses each being formed with a groove 33. A pair of rollers 3 is carried in each recess 18, the rollers each being provided at each end with stems 19 which engage the slots 33. The rollers are rotatable and are vertically slidable into place and are held in place by plates H) with upstanding lugs 81, the plates if! each being urged upwardly and consequently the lower rollers moved upwardly by a'leaf spring 8 secured at one end at 80 to the bottom of the slider. These rollers are adapted to snugly but rotatably engage in torsional substantially flat spring 4.

The flat spring 4 is preferably corrugated at 82 and the roller 3 is provided with a corresponding groove 83 to receive the corrugation. This spring 4 is widest at its center portion and is clamped between blocks H near its central portion. The outer ends of the flat spring 4 are retained by arms 34 and 5 and carried by the guide bar I. The two small blocks are screwed securely to the upper end of a short rod l3 and to this rod is fastened a metal vane or paddle 15. This rod and paddle may be considered as one piece and incombination with the torsional spring 4 form the-vibratory member of the assembly.

As the lower end of the paddle i5 is displaced in a fore and aft direction, or, in other words, perpendicular to the face of the paddle, the torsional spring 4 secured thereto will accordingly be twisted about its longitudinal axis. This resulting torsion in spring 4 causes a returning force to be exerted on the paddle, causing the latter to swing in an opposite direction. Thus the paddle is capable of a swinging'vibratory motion about the' longitudinal axis of torsional spring..4 as a center. The action of the paddle is similar to that of a pendulum except that in. a pendulum gravity is the only force acting against the impressed dis! placing force, while with the present arrangement the force of gravity is substantially supplemented by the torsion in the spring. The force required to produce a given angular displacement of paddle l5 and the angle of twist in the torsional spring 4 about its longitudinal axis depends upon the length of the spring and is exposed to such torsion. Since the rollers carried by each slider grip the spring 4 resiliently but firmly, only that part of the spring between the two sliders will be twisted. Thus as the sliders are moved towards each other the acting or effective length of the spring will accordingly be shortened and the force required to displace the paddle and twist the spring is accordingly increased. On the other hand, by moving the sliders away from each other and consequently lengthening the effective section of the spring therebetween, the force required to produce the same displacement'will be appreciably reduced. The-spring 4 is also tapered in width towards its ends in order to provide a wider range of torsion values for a given change of length of spring than would be possible with a spring of constant width. As previously explained, this effective length of the spring 4 is varied by the turning of a gear 48 which engages the racks 50 of the two sliders in order to move them either toward each other or away from each other.

When this assembly is subjected to a steady vil0 bratory motion in the plane of spring 4 having a direction perpendicular to its longest axis the paddle I5 swings back and forth with a longitudinal axis of the spring 4 as a center. Since the natural period of oscillation of paddle I5 is deterlo mined by the effective length of spring 4 between the two sliders, these two sliders may be moved part or towards each other until the natural pe-- riod of the vibratory system is the same as that of the vibration of the body which is impressed on 0 the prong 2". When so adjusted the paddle will swing in resonance with the impressed vibration. In this connectionthe well known strengthening or reinforcing phenomenon of resonance takes place and the amplitude of the swing of the pad- 5 dle i5 is considerably amplified as compared to that of the impressed vibration.

The natural period for a given amplitude swing of the vibrating system is determined by the effective length of spring 4 between the sliders. Since 30 this effective length may be varied by moving the sliders relatively to each other, it follows that the period or frequency of vibration of the paddle may be varied by so moving the sliders. Moreover, for a given angle of displacement or swing of paddle l5 and a given frequency of vibration the relative position of. the sliders will always remain the same. This being so, it is possible to calibrate the vibration impressed on the system in terms of frequency by using the distance between the sliders as a measure. This distance is conveniently indicated by means of the scale 48 and the registry of a wire arm 6! thereupon. The circular scale 46 is arranged to 'turn as the pinion 48 is rotated by means of the knob 48.

For a typical form of spring 4 and paddle I5 the relationship between the natural period of the system and the effective length of spring 4 or distance between the sliders is shown by the curves plotted in Figure 11 in which three curves are .30 shown. The left hand curve shows the relation-' ship when the paddle has a relatively small swing. In the middle curve the angle of swing is twice as great and in the right hand curve the swing is three times as great. It will thus be seenthat the relationship between the natural period of the system and the distance between the sliders is not absolute. In using the distance between the sliders as a measure of the natural period, consideration is to be taken of the amplitude of swing of paddle 15. The system may be calibrated for frequency using a given amplitude and suitable correct-ions applied to the scale thus obtained will give true frequencies for other amplitudes.

A maximum amplitude of swing attained by paddle l5 when adjusted to resonance depends upon the accelerations imparted to it by the impressed vibrations. Assuming a given frequency, the accelerations imposed are a function of the amplitude of the impressed vibration and hence the amplitude of swing of the paddle when adjusted to resonance with the vibration of the body is a measure of the amplitude of the vibration that is causing its motion.

It has been found desirable to dampen the 1110- iist-tltasullllls e ltollNt-i casing tofpermit movement" of 'the'paddle. The top of the casing 9 is substantially.jclosedgpartly tion of paddle l5 and this may be accomplished by enclosing the paddle in a casing 9 which is fastened at its upper end to the'rigid frame 49.

This casing serves to confine the air about the paddle, there being small clearances-provided between the paddle and sides and bottom" 'of'the by the frame 49 and partly by the spring 4. The front and back ends of the casing 5 are at such a distance from the paddle thatthe lattenmay-..

- *swing freely without touching the casing. The

air thus restricted. within this ,closureacts as a At its other end, the spring 4 is snaanyntteaas yoke prevents..sprilngfl..iromv moying toward or away from the guide-barbut allows endwisemotion resulting from expansion or contractionroiw the spring.

yum: v

49. There is also arranged a pin 89 extending through the'l gs and between this pin 89 and pin 90 on the irame extends a pair of tension springs 21, one 'on either sideof the casing 24. The entire casing assemblyis thus held inthese two slots 88 of the frame-by means of the springs 21, and'the lower ends of the springs 21 are con nected toa pin 89 which is approximately level with pin l2 while the other pins 90 on the frame are located at a point well above the retaining 10 slots .88., The springs. whenso placed not only pull upward to hold the pin IZ- in-its -sIots but also tend to turn the casing; assembly clockwise about the pin l2 as viewed in Fig. 2. This causes of a'rod 54 which is threaded to engage the block "56? This rod is fixed to a manually rotatable wheel. 55extending upwardly through the 'slot15" th p 52 of the casing. .Asthis rod 54 is rotated the lug 28 is caused to move forward or V backward a small distance against -,or with the. pull of the springs 21 and this results in a slight of swing of the paddle l5 on the scale 25 the casing 24, about the pin 12, the object being to paddle has secured thereto a small protruding provide a means of moving the arm l8 toward or 2;

boss l4. Extending downwardly from the boss 14 in front of paddle I5 is a light resilient striker l6 which is shown in Figure, 8 asconsisting of a small piece of wire The'form and' strength of this striker dependsnponihe range-mifrequency away from the striker 6. When the paddle is at rest it is desired that the needle '26 be over a zero position onscale 25. Since the position of the-needle 26 depends upon the relative positions of striker l5 and arm lB the turning of the wheel at which it is to work. This small piece of wire 55 and t e u ti fi Ofthe r0d'54 p o extends between the boss l4 and ampqss 5 1 vides the desired adjustment. In order to 0011115 starters thepaddle. When the paddle'i's"at tcl'balance the weight of the amplitude indicating res't'th'e striker i5 has pressed against it av short H assembly d SlidElTS bring ecenter of I angular arm 18 fastened near the lower extremity gravity of the entire mechanism to the axi of of theverticalv shaft J 1. .hThissarnrn is curved 1 d .bar-l, th'eirame is extended rearwardl'y. and so shaped that the striker l6 always hits it towards the end plate 8 to form a counterbalance 1 squarely or; mother words, perpendicular to a' ht 5|. tangent as. the arm I8 rotates with the shaft H. The mounting o the assemb y as described Nfi the upper endEf'Sha-RWH is f 'g ight consists of a light'metal case for supporting, enzg ggv wh f g g "afi n e closing andprotecting the mechanisrriEfid tress; dle 26 provided with a counterbalance 29. Above mitting to the mechanism the desired vibratory the needle is a'j hair spring'32 whichreturns nee mq ion of the body" l st ga c There is dle..2.G.toa predeterminedppsitionand keepsthe .fiJ pr vi a-IOtat b Q Q knob for ni legs are fastened to thebottom surface of the of these pins 95 is above thearm "3 and the other casing 24. Running through the two legs nearest the guide bar. and in a .directionparallel to springf 4 is a pin l2 which fits snugly into shallow vertiall with respect to the case.-

pin 96 below, so that the springs oppose each other and attempt to hold the arrn fimidw'ay be;

tween their outer ends and approximately level arm l8 in contact with striker I6. The vane 23 t pinion 8 to a j the milks f0]? Varying e fits fairly snugly within the sector'shape casingeffec v length of the torsional spring. As pre- 24 with small clearances provided betweenall of" vi sly expl ined, the p ojection -22 serves On y. the edges of the vafie and the (gaging, Thi s grt0 connect the beam 72, With the vibrating bfldy. A... rangeme-nt serves'to restrict the passage of air' and may have any convenient form depending about the vane 23 so as to dampen its motion. upon whether th'einstrument is to be hand held 0 "when thepaddle T5'Tswifigsifiiwards the arm 'IB' in ,contact withfthe body oriaste'ned. thereto. bylff me strineinvpnsnestne arm -xsrin rmntcr'it otirermeans; Tnencam zralsoserves rnsnnerf t r b mov e le. throu h them e from end i e a so th ii an r t dium of shaft I1 against the action of the hair minished the vib atory motion to the sides of -,;;'spri ng 32. Asthe paddle li-swingsaway from the-box and to the guide barthroughthe set 575 arm l8 the weak force of the hair spring and the screws 35 for mountingthe guide bar on the side high dampening effect of vane 23 in its. casing Panels of the casing. AS previously described, .-:.vdo.notiperminthe;arnnd-8;;to:iellow;the riker-;;- th s-,aaisnirota on o h uide,.,bar.aboutthe...

I6 in the return movement and hence the arm set screws passes through the center of gravity w ng j il stays in substantially the same position until of thesuspended mechanism. Hence the mechao v it"is engaged on'th'e'next iswingof the paddle 15:; nism will have no tendency to rotate about these Thus the needle 25 serves'to show'the. extreme p vo s na s it i be normally self-bal- -p sitien-reached--by th gpaddl'e s. ths nssh.ln sdr...l rd r. w vent -retain-the r nech'cforward towards the cnd-wall ll-ofthe casing-r nism apn t y s d s d p sition within '35 "Attached'to'the cover ofthe casing'2 tis an tim the case and prevent its turning far enough to l plitude sc ale 25 and -arf archfl ivhi'ch carries a" touch the top or bottom" of the case, small don screw 39 into which fits the upper end of the versprings I' may be provided so as to have one end tical shaft II. The lower end" of the shaft H of each attached to the end of the arm 5 while turnsina bearing scre'w'lSl carried by a block 20 the other end of each spring is securedto pins with upstandinglegs 20 securedthereto. Thesecarried by the side walls 53 of the casfng. One- In providing a means of turning the pinion 48 care is taken not to materially affect any rotational motion that the mechanism may have relative to the case. With this in view the pinion is placed as close as possible to the axis of rotation and is connected with the control knob 40 by means of a short shaft 44] The short shaft is provided with a flexible universal joint at both of its upper and lower ends and this universal joint may consist of a member 47 and having the form of a symmetrical cross which rotates integrally with pinion 48. Fixed on each of the four legsof .this cross are upwardly extending pins 43. Riding on these four pins is a flexible disc of fabric or rubber concentric with the pinion 48. The upper ends of pins 43 extend well above the joint assembly as a whole and are connected to the frequency scale at -97 to carry the same. 'On the cther end of shaft 44 is a similarly cross shaped member 45 carryingbn each leg adownwardly pointing pin 38. These pins engage the flexible discs 37 at points midway between the upwardly pointing pins 39 and 43 and on an equal radius.

The construction of the upper and lower universal flexible joints is the same, except that the upper flexible disc 31 is provided with a hole at its center portion so that theshaft 44 may pass through it. The cup-shaped member 42 over which the hand knob 40 is fitted, is provided with four upwardly extending pins 39 which pass through and engage the flexible disc. The cup serves to maintain within it the entire upper flexible joint. At its lower end the cup has a collar and sleeve which turn in a bearing IElZl secured to the casing top plate 52. Shaft 44 extends loosely through the sleeve IE?! to the bottom of which sleeve is secured a cam plate 63. The knob 40 may be fitted over and releasably secured to the -cup bymeans of a set screw I 3-2. The object in allowing the mechanism to rotate slightly within the casing and of balancing statically and preferably dynamically about its axis of rotation provided by the bearing screws 35 is as follows:

The phenomenon within the instrumentthat is of primary importance is the amplitude of swing of paddle I when it is adjusted to resonance with the impressed vibration. The instrument is hand held against or mounted on the vibrating body so that the impressed vibration therefrom, or the component of the vibration that is belngmzfiifdfha's' a'direction the same as that of the axis of projection 22. In other words, the direction of the impressed vibration is perpendicular to the torsional spring 4 and approximately in thesame plane. Therefore, vibratory motions or accelerations in this direction act to cause the paddle I5 to vibrate in the desired manner. Similar forces acting in a vertical direction or in -a horizontal direction parallel with the axis of spring 4 will not materially affect the swing or operation of the paddle. However, any rotational forces acting on spring. 1 about any axis parallel or nearly parallel to the axis of spring' 4 will affect the amplitude of swing of the paddle. This causes the swing to become Increased or decreased in length depending upon their relative directions. Such outslde rotational forces may arise from vibrations imparted to the hand while holding the instrument.

. They may also arise from another component of geared to the two sliders 2 as the effective length tory system is therefore supported on the pivots 35 in the manner described in order to isolate the mechanism from such rotational forces so as to make the device as far as possible a free system. In other words the case may be moved 5 rotatably slightly back and forth without the motion thereof being transmitted to the torsional spring 4 or the swinging paddle I5.

As previously stated; the present invention contemplates the application to the frequency reading on scale 46 the approximate correction necessary for different amplitudes. Assume that the instrument is subjected to a given vibration of medium amplitude and various frequencies.

A curve may be plotted to illustrate the effective lengths of the torsional spring 4 that produce resonance in the system for each of the difierent frequencies. Such a relationship is shown bythe middle curve of Fig. 11. Since scale 46 is of spring 4 is changed by the movement of the sliders, the data used in plotting this curve may be used in calibrating scale 46 directly in terms of frequency, such'as, for example, hundreds per minute. The calibration will be correct for the amplitudes used in obtaining it. For smaller amplitudes the curve shifts to the left and for larger amplitudes the curve shifts to the right. The curves also diverge as the frequency increases. If the frequency scale 46 has been calibrated for the medium amplitude represented by the middle curve, the shifting of the curves means that for larger amplitudes the scale will be read too low, and for smaller amplitudes the scale will be read too high. The error will increase with the added frequency as the divergence shows.

Figures 2, 4 and 5 show a simple arrangement for applying approximately the necessary plus or minus correction to the scale as calibrated, so that it will indicate true frequency with different amplitudes. The movable wire arm BI is used as the reference line against which scale 46 is read for calibration purposes. At its one end the arm BI is. fixed to a cam follower 62 on an arm 54 pivoted at 5? to the underside of the top plate 52. Arm 64 swings in a horizontal plane under the urging of a tension coil spring 65 connected at 64' to the arm and at 65' to the top plate, thus bringing the follower 62 into constant 50 engagement with the surface of the cam plate. The cam plate is fastened to the lower end of "the sleeve IQI of thecup 42 so as to be rotated and IE5 may be screwed to the top plate of the casing and exten d downwardly sufficiently to positively limit the pivotal movements of the indicator 59 rigidly carried by the box I50.

In the position shown in Figure 4 the pointer 59 is set to indicate a medium amplitude on the amplitude scale 25 which is the same as that with which the frequency calibration has already been obtained. In other.wor'ds,.pointer.59 in this position has been set directly from the reading obtained from the amplitude needle 25 in Figure 2.

Inasmuch as the frequency scale has already been rant/nun a resume.

calibrated at this particularaltitude no corrections are necessary. Therefore in this position the slot 65in the plate ISO is parallel to. the arm fit. wFor larger..asmliiudesthe fre uen icated by scale 46 will be inaccurate and will be a counterclockwise direction the proper distance I 'befo'retaking the reading on scale '46. This is accomplished by turr'ung theknob l! and consequently iturning the pointer '5'9' and also the slot 60 ma'clock'wi'se 'dirctibri'funtil the pointer 59 registers on the scale 25 the same amplitude shown by the needleifiiln such'..a position theslot (if! is not parallel to the reference arm 61. The end pf a m 5 wh ch l d s t e 819L99733711113313212? ca'rried'in a'counterclockwise direction. The distance. it isso carrieddepe'ndsupon the displace HEM 9 1 Ward nact ermfili q th 17.

tical rotation aids of the slot 6i). This displacement i ...s1etermi. beccp tou of t cam asmuch as the follower 62 in its engagement with n; thes -m r-e t QQmW FQ F QP eme 5 The cam is preferably so shaped that as it turns c opposite direction, resulting in the production of I a minus correction on the scale 46 H Iclairm' t V N ,y 1. In an instrument for measuring and indi s eating the amplitude and frequency. of vibration non-vibratoryi di of a given object, a self=containedunit including a case and mechanism rotatably suspended there in; said mechanism ineiilauiganiosfniaarv men; 1.

her responsive-to the vibration of said object, a

for nd means fo n erm ttently connecti g member for measuring andindicatingthe amplitudaof vibration thereof and of said object; an

indicator connected to said oscillatorymember for measuringand indicating the frequency of vi-.

' eating the amplitude and frequency of vibration" bration thereof and of said object, hand con- I trolled, e ns or a i tins lic' frequency of w n of said oscillatory member and-for-bringing the vibration thereof into resonance with' thatio'f saidgiven object. said means including a flexible V of a given 'obj ect',"a$elf=c'ontainc'd unit including an oscillatory member responsive to the vibration of said object, an indicator connected to said oscillatory member for measuring the amplitude of vibration thereof and of said object, an indicator connected to saidoscillatory mem- "ber for measuring" the frequency of "vibration thereof and of said object, hand controlled means for adjusting the frequency of swing of said 05- rice for said frequency indicator a'portion of which is adapted to be moved soas to coincide with the reading of said amplitude indicator to give a plusor minus frequencyacorrection for amplitudes other than that at which said frequency indicator is calibrated; said device includhensamei ctonsaidn oscillatory.

not

ing a pointer carried by a variable excentn'c. said excentric being operatively connected to'said fre-- quency indicator.

acase, a bar laterally pivotally suspended bysaid case, a mechanism including a frame carried-by said bar so as to. be self-balanced thereon, said mechanism including a torsional spring parallel to 'said bar and connected at its ends tosaid frame; a V 7 V paddleinplojsed in a casinggsecured to the frame, ,7

said paddle being connected at its upper end to said 'torsiorisrsprm and'wadapted to twist the same when the paddle swings in a direction persndis l t the ax s o w et e l s ri ia v shaft to said vane and pointer-against the action as.. a u msntjfe ring a dqinwc -v. eating the amplitude and frequency of vibration -too low l he correct-frequencyanaybeobtained-of a givenobject, a-self-containedunitincluding f and indicated by swingingthereference arm. 6! in and the frame, said second casing being rotatably manually adjustable about an axis parallelto said bar for adjusting the position of said arm rela- I tive to said paddle; a pair of sliders fitted with spring pressed rollers engaging the upper and lower faces'of said torsionalspring, said sliders carrying racks", apini'cn for engaging said racks;

' a manual control knob, said pinion being connected to said manual control knob for moving said sliders" toward or away from each other to vary the effective length of said torsional spring, 7

a scale operated by said knob for indicating the frequency of vibration in terms of distance be tween the adjusted-sliders and the consequently between the sliders asthe frequency of vibra-v ions? a dle i ibr sh ntgre e w j that of the given object, a correction device comprisinga control knob and a pointer overlapping said amplitude scale,'a cain plate rotated by said frequency adjuster knob, a follower for said cam plate, a reference wire pivotally connected to said follower and pivotally and slidably connected to i la t. na P n me ns inc ud n ai v controlllm'ob forbringing said. pointer and the amplitude pointer into coincidence, said refer ence wire "being adapted to move as a result of V such adjustments relative to the frequency scale to form a basis of comparison for correction pur- 4. In an instrument for measuring and indicating the amplitudeand frequency of'vibration of a'given object; a self-contained unit including a case, a bar laterally pivotally suspended by said .case, a. mechanism including a frame carried by said bar so as to be self-balanced thereon, said "mechanism including ja'torsional spring parallel to said bar and conncctedatits ends to said to twist the sanie when the paddle sv'rinssin a direction perpendicular to the axis of the torsional spring in response to'the vibrations of said object i d f i j l' si soft ie t on in .1

ill

impressed on said case, a rotary shaft connected to said frame, a second casing, an amplitude scale and a vane and pointer carried by said casing, said pointer and vane being rotatable in unison therewith, an arm carried by said shaft, a resilient member carried by said paddle adapted to engage said arm to impart rotary motion through said shaft to said vane and pointer against the action' of a return hair spring secured to said pointer and the frame, said second casing being rotatably manually adjustable about an axis parallel to said bar for adjusting the position of said arm relative to said paddle, a pair of sliders fitted with spring pressed rollers engaging the upper and lower faces of said torsional spring, said sliders carrying racks, a pinion for engaging said-racks, a manual control knob, said pinion being connected to said manual control knob for moving said sliders toward or away from. each other to vary the effective length of said torsional spring, a scale operated by said knob for indicating the frequency of vibration in terms of dis tance between the adjusted sliders and the consequently varied effective lengths of the torsional spring between the sliders as the frequency of vibration of the paddle is brought into resonance with that of the given object, a correction device comprising a control knob and a. pointer overlapping said amplitude scale, a cam plate rotated by said frequency adjuster knob, a follower for said cam plate, a reference wire pivotally connected to said follower and pivotally and slidably connected to said last named pointer, means in-- cluding said control knob for bringing said pointer and the amplitude pointer into coincidence, said reference wire being adapted to move as a result of such adjustments relative to the fre quency scale to-form a basis of comparison for correction purposes between the original reading and the varied position of the reference wire with respect to the frequency scale.

5. In an instrument for measiuing and indicating the amplitude and frequency of vibration of a given object, a self-contained unit including a case, a. bar laterally pivotally suspended by said case, a mechanism including a frame carried by said bar so as to be self-balaf1ced thereon, said mechanism including a torsional spring parallel to said bar and connected at its ends to said frame, a paddle inclos-ed in a casing secured to the frame, said paddle'being connected at its upper end to said torsional spring and adapted to twist the same when the paddle swings in a. direction perpendicular to the axis of the torsional spring in response to the vibrations of said object impressed on said case, a rotary shaftpconnected to said frame, a second casing, an amplitude scale and a vane and pointer carried by said casing, said pointer and vane being rotatable in unison therewith, an arm carried by said shaft, a resilient member carried by said paddle adapted to engage said arm to impart rotary motion through said shaft to said vane and pointer against the action of a return hair spring secured to said pointer and the frame, said second casing being rotatably manually adjustable about an axis parmiel to said bar for adjusting the position of said arm relative to said paddle, a pair of sliders fitted with spring pressed rollers engaging the upper and lower faces of said torsional spring, said sliders carrying racks, a'piniqnfor engaging said'racks, a manual control knob, said pinion being connected to said manual control knob for moving said sliders toward or away from each other to vary the effective length of said torsional spring,

a scale operated by said knob for indicating the frequency of vibration in terms of distance between the adjusted sliders and the consequently varied effective lengths of the torsional spring between the sliders as the frequency of vibration of the paddle is brought into resonance with that of the given object.

6. In an instrument for measuring and indicating the amplitude, andfrcquency of vibration of a given object, a self-contained unit including a case, a bar laterally pivotally suspended by said case, a mechanism including. a frame carried by said bar so as to be self-balanced thereon, said mechanism including a torsional spring parallel to said bar and connectedat its ends to said frame, a paddle inclosed in a casing secured to the frame, said paddle being connected at its upper end to said torsional sprizi and adapted to twist the same when the paddle swings in a direction perpendicular to the axis of the torsional spring in response to the vibrations of said object impressed on said case, a rotary shaft connected to said frame, a second casing, anamplitude'scaleand a vane and pointer carried by said casing, said pointer and vane being rotatable in unison therewith, an arm carried by said shaft,aresilientmember carried by said paddle adapted to engage said arm to impart rotary motion through said shaft to said vane and pointer against the action of a return hair spring secured. to said pointer and the frame, said second casing being rotatably manually adjustable about an axis parallel to said bar for adjusting the position of said arm relative-to said paddle, a pair of sliders fitted with spring pressed rollers engaging the upper and 35 lower faces of said torsional spring, -said sliders carryingracks, a pinion for engaging-said racks, a manual control knob, said pinion being connected to said, manual control knob for moving said sliders toward or away from each other to vary the effective length of said torsional spring, a scale operated by said knob for indicating the frequency of vibration in terms of distance between the adjusted sliders and the consequently varied effective lengths of the torsional spring between the sliders as the frequency of vibration of the paddle is brought into resonance with that of the given object, said frequency scale and said pinion being connected to and driven by the frequency adjustment control knob through the medium of flexible universal joints.

7. In an instrument for measuring and indicating the amplitude and frequency of vibration of a givenobject, a self-contained unit including a case, a bar laterally pivotally suspended by said case, a mechanism including a frame carried by said bar so as to be substantially self-balanced thereon, said mechanism including a torsional spring parallel to said bar and connected at its ends to said frame, a paddle inclosed in a casing secured to the frame, said paddle being connected at its upper end to said torsional spring and adapted to twist the same when the paddle swings in a direction perpendicular to the axis of the torsional spring in response to the vibrations of said object impressed on said case, a rotary shaft connected to said frame, a second casing, an amplitude scale and a vane and pointer carried by said casing, said pointer and vane being rotatable in unison therewith, an arm carried by said shaft, a resilient member carried by said paddle adapted to engage said arm to impart rotary motion through said shaft to said vane and pointer against the action of a return hair spring secured V to said pointer and the frame, said second casing 1 aid ackslsaidlll Tr ual control knob for movin' iio of a given object, a self-contained unit in'clud being rotatably manually adju table about an bration of the paddle is broyght into resonance aX S- parallel to saidwbarior adjusfinstheposition, .wlithflthati of the. given object, a correction device d paddla a .pair of including ointenoverlapping snLj flmplitude said sliders carry'n racks, a pinion for engaging on'bein connected to a man er'into'coincidence, a reference wire connected to said last named pointer and adapted to move" H v e as a result (SfEfiEli adjiutmntS"relative to the or arrow ilqlllncaphg gth g vary theiffectivg; iredueficyscale to form a basis of comparison for length of said torsionalspringa, l

8. In an instrument for measuring and indiand the varied position of the reference wire with eating the amplitude and frequencyvof vibrationswrespeotstolthe frequency scale, said frequency scale and the means for varying the effective ing a. case, a bar laterally pivotally suspended by length of thetorsional spring being connected swings in a direction perpendicular-to the axis "so as to be substantially self-balanced thereon,

" secured to said pointer andrthe:;frame,ssaidl sece connectedto-a manual control-knobior moving 7 springasthe frequency of vibration ofthe paddle connected at its upperend-to said torsional spring said case, a mechanism including a-frame car-V to and driven by a manual member for effecting 15 tied by said'bar'so'as'to be substantially self-ha}; the frequency adjustment through'the medium anced. t e eo s id mechanism ginclndinsiafito iii a fle ible un al -l sional spring parallel'to said bar an'd connected and adapted to twist the same when the paddle mechanism including a frame carried by said bar of the torsionallspringlin responselto the: vibraaw, saidrnechsllisminc ud a orsion l sp n tions of'said-object impressed-ensaidcase a'roing its ends fixed and extending parallel to the tary shaft connected to said frame,a second casaxis of suspension of the mechanism, an osciling, an amplitude scaleand a vane and pointer latory.emeinber including a paddle and fixedly. carried by said casing,'saidpointer and vane beconnected to said torsional spring and adapted ing rotatable in unison therewith, an arm carried to twist the same when the oscillatory member by said shaft, a resilient member carr-iedby said swings-in a direction perpendicular to the axis of paddle adapted to engagesaid arm'to impartro the torsional "springin. response to the vibrations tary motion through said shaft to said vane and "-of said object-impressed on said case-,an' amplipointer against the action of a return hair spring tude scale and a vane and pointer rotatable in unison; means for imparting movement .to said 0nd casing being rotatably manually adjustable about an axis parallel to said bar for adjusting of a return spring secured to said pointer, means the position of said-arm relative tasaidr addle afor.adjusting SaidJIALLdIlillCiQQLlelalivgi a pair of sliders fitted with'springpressed'roilers said oseil-latory-me mber, means for varying the engaging the upper and lowerlfac'es of'said tor- 7 effective length of said torsional spring, a scale for sional spring, said sliders carrying racks, a pinion for engaging said racks, saidpinion being. of the varied effective lengths of the torsional said sliders toward or awayfrom each otherto "is brought into resonancewith that ofthe given vary the effective length oi. said torsional spring," object, a correction device including a pointer h? 7 eclicllers'erigaghg Cl"l'scalel meansfor imparting"movement'thereto so ower races of said torsional spring; "as 'to'bring said pointer'aid th alr'npl'ituil'e''p'oii'it ls"- correction:purposes between the. original reading 10 '10:I1l: an instrument rormejasuiiag and in, I at its. ends to said frame,rapaddlejpclosedjn a dicating theamplitude and frequency of vibration casing secured to the'frame, said paddle being of asgiven object, a self-contained unitincluding 20 acase', a bar-pivotally suspended by-saidcase, a

vane and pointer by said paddle against the action indicatingthe-frequency of vibration in terms 40 saidpinion being connected to'and driven by the---over1apping said amplitude scale, means for imfrequency adjustment control knobthr'ough the medium of flexible universal joints. a

9. In an instrument for measuring and indicating the amplitude and frequency of vibration of a. given object, a self-contained unit including a case, a bar pivotally suspended by said case soja's'to'be'substantially self-balanced about f fine torsi'eriaifspringin resp'onse to nre visra 1g rman -instrument roltions of said object impressed on said case, a

its axis --of suspension, al mechafiisfn earr'ieogey said barincludihgaframa-a torsionalspring,

parallel to the aide of suspension of said bar and parting movement-thereto---so as to bring said pointer and the amplitude pointer into coincidence, a'reference member connected to said overlapping pointer and adapted to move as a result' of such adjustments relative to the frequency scale to forma basis of comparison for correction purposesbetween the original reading and l o ,d fr u cy scale andfthe means for varying the effective connected-atits ends to-saidframe a paddlasaiih hu in e fiQl'SQPQ 23m b ng r q l fi fii ,7

paddle being connected to said torsional spring and adapted to twist the same when 'therpaddle, swings in .a .mrection perpendicular to the axis rotary shaft connected "tosaid-frame an amplitude scale seas; vane and pbiriterrotata le'irr unison with said shait, angarmcarriedbgsaid shaft, a member carried by said paddlc adapted to engage said arm to impart rotary motion througlr said shaft to said vane and pointer against the action of a return spring secured to vsaid pointer andthe frame, means for-adjusting the'position of the axis of said'arm relative to said paddle when engaging said arm, means for varying the eiicctive length of said torsional spring, a scale for-indicating the frequency ornbration in terms of. the. varied effective lengths of the torsional's'pring as the frequency of vi- "reassess/easy aimjanual' memb'er for'eifec'ting the frequency adjustment through the medium of flexible universal joints.

said bar-seas to be substantially self-balanced thereon, a torsional spring parallel to'the axis of suspension of said bar: and connected at its ends to said frame, a paddle, said paddle being connected to said torsional spring and adapted to twist the same when the paddle swings in a di .rection perpendicular tosthe. axis of the, torsional spring in response to the vibrations of said object impressed on'said case, a rotary shaft connected to said frame, an amplitude scale and a vane I measuring-and in and pointer rotatable in unison, with said shaft,

an arm carried by said shaft, a member carried by said paddle adapted toengage s aid arm to impart a rotary motion through said shaft to said a mechanism carried by said'bar so as to be substantially self-balanced thereon, said mechanism including atorsional spring having its ends fixed and'extending parallel to the axis of suspension of the mechanism, an oscillatory member including, a paddle and fixedly connected to said torsional spring and adapted to twist the same when the oscillatory member swings in a direction perpendicular to the axis of the torsional spring in response to the vibrations of said object impressed on said case, an amplitude scale and a vans and pointer rotatable in unison, means for imparting movement to said vane and pointer by said paddle against the action of a return spring secured to said pointer, means for adjusting the relationship of said oscillatory member to said vane and pointer, and means for varying the effective length of said torsional spring.

13. In an instrument for measuring and indi cating the amplitude and'frequcncy of vibration of a given object, a self-contained unit including a case, a bar pivotally suspended by said case, a mechanism including a frame carried by said bar so as to besubstantially self-balanced there' on, a torsional spring parallel to the axis of suspension of said bar and connected at its ends to said frame, a paddle, said paddle being connected to said torsional spring and adapted to twist the same when the paddle swings in a direction perpendicular to the axis of the torsional spring in response to the vibrations of said object i-mpressed on said case, a rotary shaft connected to said frame, an amplitude scale and a vane and pointer rotatable in unison with said shaft, an arm carried by said shaft, a member carried by said paddle adapted to engage said arm to impart rotary motion through said shaft to said vane and pointer against the action of a return spring secured to said pointer and the frame, means for adjusting the relationship of said paddle to said arm, means for varying the effective length of said torsional spring, a scale for indicating the frequency of vibration in terms of the varied efiective lengths of the torsional spring as the frequency of vibration of the paddle is brought into resonance with that of the given object.

14. In an instrument for measuring and indicating the amplitude and frequency of vibration of a given object, a self-contained unit including a case, a bar pivotally suspended by said case, a mechanism carried by said bar so as to be substantially self-balanced thereon, a torsional spring having its ends fixed and extending parallel to the axis of suspension oi the mechanism, an oscillatory member fixedly connected to said torsional spring and adapted to twist the same when the oscillatory member swings in a direction perpendicular to the axis of the torsional spring in response to the vibrations of said object impressed on said case, an amplitude scale and 'a vane and pointer rotatable in unison, means for imparting-movement to said vane and pointer by said paddle against the action of a return spring secured to said pointer, means for adjusting the relationship of said oscillatory member to said vane and pointer, means for varying the effective length of said torsional spring, a scale for indicating the frequency of vibration in terms of the varied effective lengths of the torsional spring as the frequency of vibration of the paddle is brought into resonance with that of the given object.

15. In a vibratory system including an oscillatory member, means for indicating the amplitude of motion of said oscillating member, said means including a damped non-vibratory indicating needle intermittently connected by impact with said oscillatory member for maintaining a substantially constant position and consequent reading of the maximum movement of said oscillatory member within a given interval and range of movements.

16. In an instrument for measuring and indi eating-the amplitude and frequency of vibration of a given object, a selfecontained unit including a case, a bar pivotally suspended. by said case, a mechanism including a frame carried by said her so as to be substantially self-balanced thereon, a torsional spring parallel to the axis of suspension of said bar and connected at its ends to said frame, means for varying the length of the effective portion of said spring subjected to torsion, a damped swinging member connected to said torsional spring and adapted to twist. the same when the swinging member swings in a plane perpendicular to the axis of said torsional spring in response to the vibrations of said object impressed on said case, an amplitude scale and a non-vibratory damped pointer, said pointer being mechanv ically actuated by said swinging member, and means for adjusting the zerov position of said pointer on said amplitude scale.

17. In an instrument for indicating and measuring the amplitude and frequency of vibration of a given object, a sel-contained unit including a case and a vibration responsive mechanism pivotally suspended therein, said mechanism including a vibratory torsional spring, means for 

